Observing what happens to others can powerfully shape human behavior. Such other-regarding observations can motivate important social behaviors, such as cooperation and charity, as well as competition and schadenfreude. Emotions associated with social reward and punishment, such as fairness and envy, appear early in development, and disorders associated with social deficits, such as autism spectrum disorders, social anxiety disorders, and anorexia nervosa, can have devastating consequences. Converging evidence suggests that the human temporoparietal junction (TPJ) is critical for decision making in social contexts. Social deficits in numerous psychiatric disorders may arise, in part, from impaired neural circuitry with the TPJ, causing disruptions in other-regarding behaviors. The principle research goal of this project is to study the neural mechanisms underlying how the TPJ processes other-regarding preferences and behaviors. To examine this, we will perturb the region, using repetitive transcranial magnetic stimulation (rTMS), prior to a social reward-allocation task. This research complements several training goals that will help the applicant acquire new skills and prepare for a future career as a post-doctoral fellow and later as an independent investigator. These training goals will contribute to the applicant?s long-term success while providing essential new skills necessary for the proposed research. The proposed studies utilize rTMS and subsequent neurophysiological recordings to investigate two specific aims. Our first aim investigates the impact of inhibiting TPJ activity on other-regarding preferences. Our pilot data suggest that applying rTMS to TPJ at 1Hz, a stimulation protocol shown to inhibit neural processing, makes individuals less likely to reward themselves at the expense of another individual. We will continue to characterize the behavioral effects of inhibitory rTMS to TPJ as well as examine the underlying mechanisms of these effects using neurophysiological recordings. Our second aim investigates the impact of enhancing TPJ activity on other-regarding preferences. We will apply rTMS to TPJ at 5Hz, a stimulation protocol shown to enhance neural processing and characterize the behavioral effects as well as the neural effects via electrophysiological recordings. We will compare the effects of inhibitory and excitatory rTMS protocols on behavior and neuronal processing. Characterizing the changes in neuronal processing that underlie behavior would have unique translational potential, providing insight into potential treatments to target distinct impairments in other-regarding behaviors. The results of both Aims will provide insight into both the mechanisms by which TPJ contributes to vicarious reward behavior as well as the mechanisms by which rTMS affects neuronal activity and behavior under two different stimulation protocols. These findings will further our understanding of rTMS as a means to probe and manipulate the basic function of neural circuitry and provide new insight into the mechanisms underlying other-regarding behaviors in social reward and cognition.